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Biomedical subjects

E Caramelli

Publications and source records attributed to E Caramelli.

At least 37 records · Page 2Linked to original sources
PubMed1989

Liposome-nucleus interactions. Flow cytometric study on the role of the nuclear surface.

The water-soluble probe carboxyfluorescein (CF), contained in the internal aqueous phase of liposomes, was used to investigate the interaction of phospholipid vesicles with isolated nuclei. Ultrastructural analysis indicated that adherent liposomes coated the nuclear surface, and fluorescence microscopy showed that they contained quenching concentrations of the dye. Flow cytometry revealed that the transfer of the entrapped dye from the adhering liposomes to nuclei was blocked by chilling at 0 degrees C. Chase experiments demonstrated that the most reliable mechanism of dye transfer involved fusion phenomena between the liposomal and the nuclear membranes. After the release of the fluorophore into the nucleus, empty liposomes could withdraw the intranuclear soluble fraction of the dye.

Animals↗
PubMed1988

Changes in ribonucleoprotein particle and chromatin organization induced by liposomes in isolated nuclei.

Nuclei isolated from rat liver, incubated in the presence of liposomes of different phospholipids, undergo typical modifications: chromatin dispersion and reduction of the interchromatin granules in nuclei incubated with negatively charged liposomes and increase of the chromatin density and of the number and size of the interchromatin granules in nuclei incubated with neutral liposomes. The possibility that the observed modifications are caused by an impairment of the transport and translocation of ribonucleoproteins belonging to the inner nuclear matrix, is suggested by the results obtained by radiotracer techniques on the release of RNA from liposome-incubated nuclei.

Animals↗
PubMed1988

1H-NMR relaxation study of the liposome--nuclei interaction.

Phospholipidic liposomes can influence DNA template availability for RNA synthesis when interacting with isolated nuclei by enhancing (when the phospholipids are negatively charged) or by inhibiting (when they are neutral) trascriptional activity. The analysis of the 1H-NMR relaxation behaviour of isolated nuclei, of Small Unilamellar Vesicles (SUV) and of the SUV-Nuclei system has been undertaken to elucidate the mechanism of the interaction between the nuclear core and the phospholipids.

Animals↗
PubMed1987

Influence of phosphatidylserine on endogeneous RNA synthesis in isolated rat liver nuclei.

The possible involvement of anionic phospholipids in the transcriptional process was studied in isolated rat liver nuclei synthesizing RNA in the presence of phosphatidylserine, which was employed in the form of multillamellar liposomes as a means of delivering the lipid to the nuclei in aqueous medium. The divalent ion requirement for RNA synthesis and the properties of the incubation mixture were not significantly modified by the phospholipid, which increased the rate and the extent of the incorporation of 3H-UMP without changing the endogeneous degradation pattern of the product or affecting the activity of a particular RNA polymerase, as indicated by the sensitivity to amanitin. The thin layer chromatography analysis of the alkaline hydrolysates of the RNA showed that the stimulation involved an increase of the total polyribonucleotide elongation rate. The size of the product was essentially unchanged in the presence of phosphatidylserine, as demonstrated by the qualitative overlapping of the sedimentation profiles of control and lipid treated samples in formamide-sucrose gradients. The release of the H1 fraction from intact nuclei occurring with phosphatidylserine indicated that the DNA template availability was increased by a partial removal of the restrictions imposed by histones, as suggested also by the comparison with heparin and Sarkosyl. These evidences, together with the data accumulated on the occurrence of lipids in chromatin and nuclear matrix, and on their changes related to cell growth, differentiation and malignant transformation, allow a better definition of the role that phospholipids might play in regulating the DNA template availability in the cell.

Amanitins↗
PubMed1986

Flow cytometric analysis of liposome-nuclei interaction: transfer and intranuclear release of carboxyfluorescein.

Flow cytometric analysis of the transfer of liposome-encapsulated carboxyfluorescein to isolated rat liver nuclei indicated that the fluorophore is actively taken up in this form, while negligible amounts are transferred when the dye is free in the reaction medium. The kinetic analysis of the uptake indicated a time- and dose-dependent reduction of the slope in the absence of transport saturable sites on the nuclear surface and of quenching phenomena. The comparison between entire and membrane-deprived nuclei demonstrated that the initial rate of uptake was higher in the absence of the complete nuclear envelope. The intranuclear binding sites were considered on the basis of the fluorescence distribution and of quantitative estimates of the amount of linked dye. The possibility of employing flow cytometry to monitor the interactions between liposomes and isolated nuclei by means of a fluorescent probe is discussed.

Animals↗
PubMed1985

Response of isolated nuclei to phospholipid vesicles: a two dimensional gel electrophoresis analysis of H2SO4 soluble nuclear proteins after treatment with phosphatidylserine.

H2SO4 soluble proteins extracted from nuclei incubated with phosphatidylserine multilamellar vesicles (PS MLV) have been analysed by means of two-dimensional gel electrophoresis with particular attention to the uH2A fraction. A reduction of H1, H1 degrees and proteins A5, B7, B15 and B23 has been observed in lipid treated nuclei, while the core histones, as well as uH2A are unaffected by liposome treatment. Since these proteins show in vitro the same binding affinity for PS, their behaviour appears to be related to difference in localization in the nucleosome, responsible for their variable accessibility in the chromatin. These results might explain how this phospholipid induces a decondensation of chromatin and a stimulation of RNA synthesis.

Animals↗
PubMed1984

Conformational changes of nuclear chromatin related to phospholipid induced modifications of the template availability.

The phospholipid involvement in the regulation of the functional and structural properties of isolated nuclei has been studied by analyzing the composition and the possible function of the nuclear matrix bound phospholipids in rat liver and murine erythroleukemic cells. The digestion of the matrix phospholipids with phospholipases results in the release of essentially all the newly replicated matrix DNA. The exogenous addition of liposomal phosphatidylserine to rat liver nuclei induces chromatin structural changes consisting in a disaggregation of the heterochromatin, probably mediated by the matrix remodeling, and in a transition from the solenoid fiber to the nucleosome filament, due to the removal of the histone H1. These effects occur through a direct interaction of phospholipid molecules with the inner nuclear components, as demonstrated by carboxyfluorescein transfer and electron microscope autoradiography.

Animals↗
PubMed1984

Response of isolated nuclei to phospholipid vesicles: analysis of the nuclear proteins after treatment with phosphatidylserine and phosphatidylcholine and comparison with heparin.

Phospholipid liposomes affect the histone pattern of isolated rat liver nuclei. Multilamellar vesicles (MLV) obtained with phosphatidylserine (PS) release a large amount of the lysine rich histones, while those obtained with phosphatidylcholine (PC) do not induce significant changes with respect to controls. This different response has been compared to the effects obtained with Heparin, which slightly modifies the relative ratio of the histone fractions. These data might account for the mode by which phospholipids induce transitions of the chromatin structure and changes of the endogenous RNA polymerase activity.

Animals↗
PubMed1984

Transfer of liposome-encapsulated carboxyfluorescein to isolated nuclei.

The interaction between phosphatidylcholine vesicles and isolated rat liver nuclei has been examined by studying the uptake of the fluorophore carboxyfluorescein. The kinetics of transfer of the dye, analyzed by flow cytofluorimetry with a Fluorescence Activated Cell Sorter (FACS IV), indicate an efficient delivery to the nucleoplasm. The results reflect a liposome-nuclear membrane interaction which may contribute to the processes which underlie our previously described morphological and functional changes in isolated nuclei treated with phospholipids.

Animals↗
PubMed1983

Association between centriole and nuclear matrix in human lymphocytes.

Nuclear matrices, purified from normal and chronic lymphocytic leukemia lymphocytes, exhibit a close association with the centriole. This finding suggests that the nuclear and cytoplasmic skeletal systems are linked by transmembrane connections represented by nuclear matrix constituents. This could account for the observed synchrony between transformations of the centriole and particular nuclear events which take place during the cell cycle and suggests that the nuclear matrix, besides being involved in DNA replication and chromosome condensation, should affect the centriole cycle which controls the cytoskeleton organization.

Cell Division↗
PubMed1981

[Karyotype in chronic myeloid leukemia in a blastic crisis. I. Monosomy 16].

One case of Chronic Granulocytic Leukemia is reported, in which the patient showed, during a blastic crisis, an aneupolid cariotype 45, XX, t (9; 22) (q34; q11), -16. This paper emphasizes the rare involvement of the chromosome 16 in Leukemias, and stresses the high frequency of the alterations of the chromosome group E in the course of blastic crisis.

Chromosome Aberrations↗
PubMed1981

[Karyotype in chronic myeloid leukemia in a blastic crisis. II. Trisomy 17].

One case of a patient with Chronic Granulocytic Leukemia showing a double Ph' together with trisomy 17 during blastic crisis is reported. The Ph' chromosome resulting from a standard translocation of the chromosomes 9 and 22 was present in all the 16 mitoses observed, while the trisomy 17 was found in 15. This case is an additional contribution which demonstrates the presence of the alterations of the chromosome group E during the blastic crisis.

Chromosomes, Human, 16-18↗
PubMed1981

[Cytogenetics in bone marrow transplantations. I. Bone marrow aplasia].

A bone marrow transplantation has been carried out in a patient with bone marrow aplasia. Besides the cytochemical and haematological tests, the cytogenetic analysis has been performed to check whether the transplantation was successful. In this case the donor was the patient's sister, so that the presence of the chimere has been used as a criteria for judging the conditions of the transplantation. the cytogenetic analysis, furthermore, is suitable to detect other chromosome abnormalities, which can represent a condition of instability of the transplanted cells and are probably an early expression of the transplanted bone marrow.

Adolescent↗
PubMed1981

[Cytogenetics in bone marrow transplantations. II. Acute lymphocytic leukemia].

In this we report cytogenetic data concerning two patients with Acute Lymphoblastic Leukemia (ALL), submitted to bone marrow transplantation. In one of two patients the chimere was present while in the other case it was absent, since the donor and the acceptor were of the same sex. However even in the latter case, the cytogenetic analysis was useful and led to the identification of endomitosis and endoreduplication phenomena, which are signs for an unlucky prognosis.

Bone Marrow Transplantation↗
PubMed1981

[Characterization of the convoluted seminiferous tubule wall. I. Ultrastructural aspects after the ligation of the vas deferens and the efferent tubules].

The structure of the wall of the rat seminiferous tubules has been studied by electron microscopy. No significant modifications have been revealed after the ligature of the vas deferens while on the contrary the ligature of the efferent ductules produces a reduction of the contractile filaments and of the pinocytosis vesicles, as well as an increase of the amount of collagen fibers in the basal membrane.

Animals↗
PubMed1981

Effect of phospholipid vesicles on endogenous RNA polymerase activity of isolated rat liver nuclei.

Negatively charged phosphatidylserine vesicles increase RNA polymerase activity of isolated rat liver nuclei, whereas inhibition is obtained with sphingomyelin, phosphatidylethanolamine, phosphatidylcholine, and phosphatidylinositol vesicles. The effect of phosphatidylserine on template activity is dose-dependent and similar to that reported for acidic polymers like heparin. These data indicate that the nature of the polar head is mainly responsible for the different effects and suggest that the phospholipids may be involved in mediating gene expression.

Animals↗
PubMed1981

Interactions among DNA, metallic ions, and lipids.

Interactions amond DNA, phospholipids, and Cu2+ ions have been investigated by means of thermal denaturation technique. The results indicate that phosphatidylserine and sphingomyelin interact with Cu2+ ions, which are able to prevent the chance of binding of the phospholipids to the double helix. This interaction is strictly dependent upon the concentration of the divalent cation and reduces the capability of the employed phospholipids to modify the thermal stability of DNA.

Chemical Phenomena↗